Grinding wheel



March 6, 1962 w. OSENBERG 3,023,551

GRINDING WHEEL Filed May 12, 1958 2 Sheets-Sheet 1 INVENTOR y W 05 EN BERG wim-mmma March 6, 1962 w. OSENBERG 3,023,551

GRINDING WHEEL Filed May 12, 1958 2 Sheets-Sheet 2 Fig.9

// II M Wwm- OSENBERG INVENTOR United Sates atet fifice 3,023,551 Patented Mar. 6, 1962 The present invention relates to grinding wheels and more particularly to side grinding Wheels.

According to the present invention a grinding wheel comprises two or more grinding discs or disc-like portions, the diameter of each of which is large compared with its thickness, said disc being spaced apart axially and rigidly secured to one another to form a unitary structure.

In one embodiment of the invention the grinding discs may be secured to and spaced apart by one or more spacing members.

In another embodiment a grinding disc has radially extending projections which serve to keep it axially spaced from and cemented to adjacent wheels or to projections of adjacent wheels.

In a further embodiment a grinding wheel is manufactured by a single body, grooves being made in said body during the manufacture thereof to define two or more grinding discs joined together by ribs.

In a still further embodiment each grinding disc has embossed concentric annular or radial depressions and elevations, the individual discs being rigidly connected by cementing or welding together the elevations of adjacent discs whereby to keep said discs axially spaced apart.

During grinding a face grinding wheel often has to be advanced in the direction of its axis of rotation, during which it becomes exposed to lateral loads; however a grinding wheel constructed in accordance with the present invention may be capable of meeting these stresses.

The thinness of the individual grinding discs leads to the result that their narrow edges penetrate easily during grinding into the workpiece to be machined in a similar manner to the edges of cutting-off Wheels or of flexible grinding discs as they engage with the surface of the workpiece to be machined.

In known grinding wheels which are very wide, the cutting rate is limited by the feature that the pore areas of the disc do not permit the removal of the ground-away material to an extent corresponding to the actual cutting ability of the embedded abrasive grain. In order to assist the removal of the ground-away material, highly porous grinding wheels have been developed in the last few years which, however, owing to their specific construction, have a comparatively high rate of wear and are therefore expensive to use. With a grinding wheel of the present invention, however, the abrasive grains are retained densely and securely in a bonding which may vary according to the proposed use of the grinding wheel. If it were desired to use such a strong and compact bonding i.e. such 7 The abrasive grains may be bonded ceramically or by means of thermosetting or thermoplastic synthetic material.

In the following examples, a few mixing ratios and pressures and temperatures are given at which the setting of grinding discs takes place which are manufactured with the use of synthetic resin bondings. In the examples the hardening times are also listed.

Example I Abrasive Grit size Quantity, g.

Boron carbide a=2.83 to 2.38 mm 133. 2 b=0.84 to 0.71 m1n 138.0

Binder Quantity, Kglcm. Tempera- Time,

g. pressure ture, C. min.

1. Phenolic resin (resole) 60. 4 300 10 2. Phenolic resin (novolak 59.4 300 160 3 3. Cresolic resin (resole). 58.0 300 160 10 4. Oresolic resin (novolak) 57.0 300 160 3 5. Solid melamine resin 69. 3 300 160 3 6. Polyamide 53. 2 1, 000 solidification by cooling Example II Abrasive Grit size Quantity, g.

Precious corundum 2.83 to 2.38 mm 199. 5

Binder Quantity, Kg./ :m. Tempera- Time,

pressure ture, C. min.

1. Phenolic resin (resole). 64. 4 300 160 10 2. Phenolic resin (novolak 63. 5 300 160 3 3. Cresolic resin (resole) 62.0 300 160 10 4. Oresolic resin (novolak) 60.9 300 160 3 5. Solid melamine resin 74. 0 300 160 3 6. Polyamide 56. 8 1, 000 solidification by cooling The removal of ground-away material takes place when using a grinding wheel of the invention because grooves extend between the narrow grinding edges of the individual grinding discs which discs are very thin but have a very solid binding, said grooves preferably having a width approximately equal to the Width of the individual grinding discs.

A rigid connection of the individual grinding discs of the grinding wheel and spacing members, which may, for example, be hollow members, honey-comb plates or the like or sponge-like material, provided between the discs is necessary. These members used for distance purposes are connected to the faces of the individual grinding discs by cementing with the use of very strong setting adhesives or the like known for these purposes. If spongy material is used for spacing members either sponge plates can first be produced which are then connected in the above mentioned manner to the faces of the grinding discs or the spongy material is foamed between the individual grinding discs previously arranged in a moulding tool.

In the case of a grinding disc which is comparatively wide, several narrow grinding edges can be formed by inserting rotating, if preferred, also adjacently disposed, milling tools radially through the side of the grinding disc into the body of the disc and turning the disc through a suitable angle before the final firing of the disc. I p v If it is desired to avoid the use of spacing members, cross pieces or ribs or the like, preferably radially extending, may be formed in the faces of the individual grinding discs during the manufacture of the disc, by pressing or, before the final firing, by the cutting away of material from the face of the disc. Grinding discs manufactured in this manner with narrow moulded cross pieces can then be combined together by cementing to form a grinding wheel or a grinding roller.

If spacing members in the form of radial strips are used as distance pieces between the grinding discs, it is advisable to provide both the face of each disc and the sides of the strips coming into contact therewith, with teeth which interengage when placed together. This feature increases the centrifugal strength of the face grinding Wheel.

Face grinding wheels according to the invention may be used for any grinding operations such as for internal and external cylindrical grinding, and more particularly, also for surface-grinding preferably of semi-finished products, slabs, sheet bars, billets and the like. As is well known, most semi-finished products have to be surface treated so that flaws due to previous rolling operations can be removed. With reciprocating grinding machines known for this purpose, side grinding wheels of comparatively large diameter, and width are used which are able only very inefficiently to remove the groundaway material for the previously described reasons. This disadvantage cannot be removed merely by increasing the grinding pressure, for this results in temperatures in certain areas of the workpiece being machined which lead to unacceptable formations of cracks within the surface of the workpiece.

With the use of face grinding wheels constructed according to the present invention, owing to the simultaneous engagement of several adjacent narrow grinding edges on the one hand, and owing to the spaces between the grinding edges on the other hand, the grinding rate per unit of time can be increased several times, the production of comparatively high temperatures on the surface of the workpiece is much reduced, owing to the spacing and ventilation obtained between the individual grinding discs. Moreover, the specific consumption, that is, the wear of the grinding wheel can be reduced by the use of dense and strong bonding.

Since thermosetting materials, which are even stable under sparking, are now available as bonding for the abrasive grains, workpieces such as semi-finished products can also be superficially ground in a warm condition with a grinding wheel constructed according to the present invention. This is not practicable with known grinding wheels which are comparatively wide, since additions and deposits would immediately appear on their surface.

Since the high strength of the bonding which results from the use of thermosetting plastic permits a high peripheral speed for grinding wheels the occurrence of high temperatures in the region of the grinding edges of the grinding wheel is hereby suppressed. All materials hitherto employed as bonding for thin grinding discs may be used in the present invention. Likewise, of course, the nature of the abrasive material and the granulation may be greatly varied. It is also possible to construct the same grinding wheel with individual grinding discs of various construction with respect to their bonding and granulation.

Spacing members such as distance pieces, strips, honeycomb plates and the like, connected undetachably to the discs, may be of a material other than the bonding. For example, ceramically bonded grinding discs can be connected together by plastic distance strips, by honeycomb plates of plastic or by spongy material, or alternatively grinding discs having a very strong synthetic bond, similar to that of flexible discs can be combined by metal distance strips or by sandwich plates, i.e. hollow metal plates, at a space from one another to form a rigid grinding wheel.

Finally the grinding wheel may also be composed of individual discs segments which in turn are built up in a plurality of stages.

Instead of hollow strips, honeycomb plates or the like, the discs themselves may have concentric or radial depressions and surfaces for the formation of large spaces between the discs. The shaping of the discs may be so arranged that contact surfaces are obtained for cementing or welding adjacent discs. Thus .two or more discs may be combined to form a grinding wheel or roller.

The invention will be further described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a plan view of the face of a side grinding wheel according to one embodiment of the invention and comprising three thin discs spaced apart by hollow spokes,

FIG. la is a section on the line II of FIG. 1,

FIG. 2 is a side elevation of the grinding wheel shown in FIG. 1.

FIGS. 3 and 4 are side elevations of a part of a grinding Wheel according to other embodiments of the invention, comprising three discs spaced apart by distance plates which have radial embossments or the like.

FiG. 5 is a side elevation of a part of a grinding wheel comprising three discs spaced apart by spongy material,

FIGS. 6 and 7 are side elevations of a part of a grinding wheel comprising three discs spaced apart by narrow cross pieces extending radially from the faces of the discs.

FIG. 8 is a side elevation of a part of a grinding wheel or a disc for a grinding wheel comprising three thin discs, in which several narrow grinding edges are formed by radial grooves are made in the grinding disc before the final firing operation during manufacture.

FIG. 9 is a cross section through a side grinding wheel formed by four thin embossed discs.

FIG. 10 is a side elevation of a half of the grinding wheel according to FIG. 9.

In FIGS. 1 and 2 thin grinding discs are indicated by 1, 1" and 1', a hub, on which these discs are mounted, by 2, and square hollow spacing strips inserted radially between the discs by 3. The discs 1, 1". and 1 may have a very strong synthetic binding with fabric inlays, the square tubes 3 may be wound from strong paper, also with the use of plastic bonds. The discs 1, 1" and 1 are mounted on the hub 2 with the radial insertion of the square tubes 3 with the use of a setting adhesive. According to FIG. la the outer surfaces of the grinding discs as well as the square tubes 3 or the like radially arranged between said discs, are provided with serrations gearing into each other to increase the centrifugal strength of the grinding wheel. The serrations of the square tubes 3 have the reference numeral 3' and the corresponding serrations of the discs 1', 1" and 1' have the numeral 3".

Between the discs 1', 1" and 1 grooves are obtained by this construction which makes it possible to operate with high grinding rates. As is well known the grinding discs render possible with synthetic bonding and textile inlays the use of high cut-ting speeds of for example about 90 metres per second and the grinding of comparatively large quantities of material per unit of time. This grinding rate is limited by the width of a synthetically bonded grinding disc. If a grinding disc is for example 65 mm. or mm. wide, as is the case of reciprocating machines for the grinding of the surface of billets for sheet metal manufacture, the grinding rate is limited by the feature that insuflicient cuttings can be removed. The grinding discs are therefore inclined at an angle to the surface to be ground so that only a comparatively narrow edge is engaged.

The grinding rate of a grinding wheel constructed according to the present invention may be increased by pressing the wheel against the surface of a workpiece to to be ground and inclined at a predetermined angle thereto as indicated at the left hand side of FIG. 2. Examples of possible positions of the surface of the workpiece relative to the grinding wheel are shown in FIG. 2 by the dotted lines 9 and 9'.

The grinding wheel becomes somewhat conical .after curvature. .to: be ground, the final cylindrical outline of which is ingrinding away a certain amount of material, the material removed being indicated in FIG. 2 by 10. By inclining the grinder in the opposite direction this change of profile may be reversed again.

When grinding tubes and bars of circular cross section, the face grinding wheel by changing its profile by loss of material as indicated by on the right of FIG. 2 adapts itself to the cross section of the tubes or bars.

.Thus each of the grinding tracks I, II, III which separately take part in the grinding operation are given some By turning round the tube or bar material,

dicated in FIG. 2 by 8, a thickness S is cut away in stages. The complete circumference of the material which is indicated by 8', can thus be removed by grinding.

The grinding wheel may therefore have curved grinding tracks I, II and III or conical, grinding tracks I, II and III. If the side grinding wheel shown in FIGS. 1 and 2 were solid, this would mean that over its entire width b and thus over the curve C to D it would have no interruptions due to cutting grooves, and then it would not be practicable to cut away material at such a fast rate such as for example from the outer surface of a tube (see FIG. 2 right hand side).

The space between grinding discs of small thickness is obtained in the embodiments indicated in FIGS. 3 and 4 by inserting between them metal or non-metal, honeycomb or corrugated embossed plates 3 and then welding or cementing. The corrugations preferably extend radially. In the embodiment of FIG. 5 this space can be obtained by the introduction of spongy material '6 which can be cemented in pre-formed slabs between the discs, or, after suitable positioning of each grinding disc in a closed moulding tool, by the supply of a setting spongy material.

If it is desired to avoid the use of distance pieces, slabs of spongy material and the like the radial narrow cross pieces or ribs 4 shown in the embodiments of FIGS. 6 and 7 can be simultaneously moulded during the manufacture of a grinding disc. These ribs 4 render possible a spacing dependent upon their thickness. By using a setting adhesive the manufacture of a strong, undeatchable connection between the individual grinding discs then becomes possible so that a rigid side grinding wheel forming a coherent unit is obtained.

A very important embodiment of the invention is shown in FIG. 8 in which, with a side grinding Wheel of comparatively large width, the narrow grinding edges 1, 1" and 1" are produced by radially introducing rotating milling tools before the final firing of the grinding disc (as indicated by 7 in, FIG. 1) through the cylindrical side of the grinding disc into the grinding body, whereupon the entire disc is turned through an angle in the direction of the arrow so that the point A, compare FIG. 1 moves towards the point B. In this manner the cutting grooves 5 are cut out by the rotating milling tools 7 before the final firing operation during manufacture.

FIGS. 9 and 10 show an embodiment of side grinding machine comprising four separate grinding discs 11', 11", 11" and 11". These grinding discs have concentric, groove-like depressions 12 which appear in the side elevation (FIG. 10) as concentric circles. By suitably shaping or embossing the four grinding discs 11', 11", 11 and 11"" contact surfaces 15 can be obtained which make it possible to combine the four grinding discs as shown in the drawing into a strong unit with the use of a setting adhesive or by welding. The adhesive is applied to the annular contact surfaces 15. By uniting, as shown in FIG. 9, embossed grinding discs, the large spaces 14 are produced making it possible to grind cool even at high cutting speeds. The cavities 16 shown shaded in FIG. 9, of the grinding body can be suitably filled so that the grinding wheel has special stability.

The bonding of the grinding discs may be of any desired kind, in particular, thermosetting plastics may also be used for a bonding as used in the manufacture of socalled flexible discs, separating discs and the like. In addition the discs .11, 11", 11" and 11"" can be constructed in layers and contain a reinforcement of fibre material so that the entire grinding body has a special strength and can work at high peripheral speeds.

Since the grinding discs, particularly those with fabric reinforcements, may be very thin, it is possible to unite two suitably profiled, thin discs of large diameter to form a strong cool-cutting cutting-01f wheel. The embossing method which may be employed makes it possible to construct the cutting-off wheel with a recess, that is to say with a reduction in the thickness of the wall towards the centre of rotation.

The groove-shaped depressions shown in the drawing concentric with the axis 18 of the grinding wheel may be replaced by radial groove-shaped embossings. This form of the individual grinding discs corresponds in this case to that of a wobble milling cutter (as used for the turning and trueing of grinding discs). Such shaped grinding discs may also be assembled to form a rigid side grinding wheel.

Naturally, the grinding discs forming side grinding wheels constructed according to the present invention may be of any desired dimensions. In addition to the construction of grinding wheels with three or four operating edges, as shown in the figures, multistage grinding rollers of comparatively large width may also be manufactured which may be used specifically for internal cylinder grinding such as for tube grinding. The side grinding wheel may also be constructed of disc segments which form in themselves a coherent unit and also have grooves and radial spacing members.

What I claim is:

1. A peripheral grinding wheel comprising a plurality of thin grinding discs spaced from one another, said grinding discs consisting of abrasive grinding granules having a bonding agent, spoke-like spacing members arranged between said grinding discs connected to said discs having about the thickness of half a disc, said spacing members comprising a soft material which easily wears out during grinding, said spacing members being formed as hollow profile members.

2. A peripheral grinding wheel as set forth in claim 1 wherein said discs and spacing members are glued to one another.

3. A peripheral grinding disc as set forth in claim 2 wherein the contacting surfaces of said spacing members and discs are provided with interlocking serrations.

4. A peripheral grinding disc as set forth in claim 3 wherein the contacting surfaces of said spacing members and discs are provided with interlocking serrations.

5. A peripheral grinding disc as set forth in claim 4 wherein the contacting surfaces of said spacing members and discs are provided with interlocking serrations.

6. A peripheral grinding disc as set forth in claim 4 wherein said grinding discs constitute concentrical protrusions and recesses having a size comparable to the thickness of a disc.

7. A peripheral grinding disc as set forth in claim 6 wherein said protrusions and recesses are staggered.

8. A peripheral grinding wheel as set forth in claim 1 wherein said spacing members comprise honeycombed impressed annular plates.

9. A peripheral grinding wheel as set forth in claim 1 wherein said spacing members comprise wave-like impressed annular plates.

10. A peripheral grinding disc as set forth in claim 1 wherein the contacting surfaces of said spacing members and discs are provided with interlocking serrations.

11. A peripheral grinding wheel comprising a plurality of thin grinding discs facing one another and spaced from one another, said grinding discs consisting of abrasive grinding granules having a bonding agent, said grinding discs having radially extending side projections to which saiddiscs are glued.

12. A peripheral grinding disk comprising a plurality of individual thin grinding disks spaced from one another, said grinding discs consisting of abrasive grinding granules having a bonding agent, said disks having projections which are glued together at their sides which face each other, and said projections on said disks being concentric thereby forming recesses between said disks having a thickness equal to a cross section of a disk and giving to each disk 2. zigzag-like formation along a radial line.

References Cited in the file of this patent UNITED STATES PATENTS Larnson Aug. 20, 1912 8 Curtis May 13, 1919 Conners July 5,1921 Osborn Nov. 7, 1922 King ....2 Feb. 8, 1927 Legge Sept. 20, 1932 Taylor Apr. 18, 1933 Webster Apr. 13, 1937 Solstrom Sept. 7, 1937 Anderson Sept. 28, 1937 Todd et a1 Dec. 12, 1939 Allison Dec. 28, 1948 Belcher Mar. 18, 1952 Veletta July 5, 1955 FOREIGN PATENTS Switzerland June 30, 1950 Germany Nov. 6, 1940 France Aug. 20, 1941 

